Light rust removal can be accomplished with a ScothBrite pad (not sandpaper). For heavier rust removal, and to get into the rail ends where the steel pins go, using electrolysis is the best way to go. Electrolysis is what causes oxidation in the first place, and electrolysis is used to remove it. It is the method used by museums and restoration companies. Easy to set up and inexpensive, it will get track, trains, and anything else rust free in a short time without damaging good metal, and without caustic chemicals.
Larry